Carl Icahn continues to think the world’s most valuable company is undervalued. And he won’t leave Apple Inc. alone until it agrees with him.

The activist investor and 77-year-old is sticking to his idea that the technology giant should borrow $150 billion and then buy back shares worth that same amount. At his apartment last night, Mr. Icahn regaled Apple CEO Tim Cook with histhesis over dinnerand then took the airwaves Tuesdayto reiterate his “no brainer.” And reiterate some more.

Here’s what we learned after nearly 25 minute interview on CNBC:

Carl Icahn is not a quitter: “I can’t promise you the stock is going to go up and I can’t promise you they are going to do the buyback, but I can promise you that I’m not going to go away without them hearing a lot more about that,” Mr. Icahn told CNBC. “We are going to meet again and keep the discussion going.”

This isn’t the Dell board he’s dealing with, but he’s watching: Mr. Icahn has made no secret of his dislike of board chicanery, but, so far, he doesn’t feel like Apple’s board is up to anything. While he said the one point the “cordial” dinner got “testy” was when he pushed back against Apple CFO Peter Oppenheimer’s comment that he board had decided on $60 billion in buybacks. “That’s not enough. The answer can’t be that’s what the board decided,” Mr. Icahn said. But he also went to lengths to complement both Mr. Cook and the board. “I think, and I told this to Tim, I told him he’s doing a damn good job.” He also said “I do respect business judgment of a board I think is capable, and I think Apple is doing a good job.”

Mr. Icahn isn’t threatening anyone, but they should listen: The investor declined several times to “put words in Tim’s mouth” about the company’s intentions. However, while he stopped short of actually saying what else he could do to force Apple’s hand, he vaguely said it probably involves more than dinner in New York. He has about $2 billion position, which would be far less than 1% of the stock, but Apple would “respect. And while he feels “very strongly,” and he hasn’t begun to consider the options if the board says no,“I think it’s fair to say we have a lot of options.”

Tim Cook goes to bed early: Mr. Icahn said dinner ran longer than expected. After starting at 7 p.m. ET, it ran until about 10:30 p.m., Mr. Icahn estimated: “It was past Tim’s bed time, we joked,” he said, explaining the two work on different schedules. “Tim goes to bed early.”

Mr. Icahn has a personal cook. His name is also Tim, which created confusion. He doesn’t invest: Mr. Icahn told a little anecdote about his chef asking why Mr. Icahn said on twitter he was having dinner with Tim. After all, Mr. Icahn almost always has dinner with his chef. He added his chef, who has fed many top CEOs over the past decade and has presumably been in the room for powerful discussions, doesn’t invest. “He makes a damn good income … he just doesn’t play the market,” Mr. Icahn announced.